3. Electronic Theses and Dissertations (ETDs) - All submissions
Permanent URI for this communityhttps://wiredspace.wits.ac.za/handle/10539/45
Browse
2 results
Search Results
Item Quasinormal modes for a spin-3/2 field in a reissner-Nordstrom background(2017) Ngcobo, Xolane IgnitiousIn this dissertation I will present quasinormal mode results calculated using two approximation methods; the Wentzel-Kramers-Brillouin (WKB) and the Asymptotic iteration method (AIM). I will rst do two brief examples, where we will compute the QNMs for a scalar eld in a Schwarzschild and Reissner-Nordstr=om background, then the QNMs for a massless Dirac spinor in a Schwarzschild background. These two examples will help build some intuition leading up to the main subject of this dissertation - the spin-3/2 field. The use of the WKB method is motivated by the works of Sai Iyer and Clifford M. Will [1], where they applied the WKB approximation method to computing the QNMs for black holes perturbed by fields. The AIM approximation method used here is the improved AIM approach of Cho et al [2]. This work is aimed at understanding the behaviour of spin-3/2 fi eld in a blackhole background, and since the Schwarzschild background for the spin-3/2 has been intensively studied, I have decided that the Reissner-Nordstrom background will be very interesting to study as it is a charged background.Item Quasinormal modes for spin-3/2 particles in N-dimensional Schwarzschild black hole space times(2016) Harmsen, Gerhard ErwinThis dissertation will focus on spin-3/2 perturbations on N-dimensional Schwarzschild black holes, with the aim of calculating the numerical values for the quasi-normal modes (QNMs) and absorption probabilities associated with these perturbations. We begin by determining the spinor-vector eigenmodes of our particles on an (N-2)-dimensional spherical background. This allows us to separate out the angular part and radial part on our N-dimensional Schwarzschild metric. We then determine the equations of motion and e ective potential of our particles near the N-dimensional black hole. Using techniques such as the Wentzel-Kramers-Brillouin and Improved Asymptotic Iterative Method we determine our QNMs and absorption probabilities. We see that higher dimensional black holes emit QNMs with larger real and imaginary values, this would imply they emit higher energy particles but that these particles are highly dampened and therefore would be di cult to detect. The results of the QNMs make sense if we also consider the e ective potential surrounding our black holes with the potential function increasing with increasing number of dimensions.